Mercury switch



Jan' 7, 1930 w. R. WALKER MERCURY SWITCH Fiied sepa-18, 1928 R v. m imfm f/ l@ A Patented Jan. 7, 1930 UNITED STATES PATENT OFFICE WARREN R.WALKER, F SHORT HILLS, NEW JERSEY, ASSIGNOR TO COOPER HEWITT ELECTRICCOMPANY, 0F HOBOKEN, 'NEW JERSEY, A CORPORATION OF NEW JERSEY MERCURYSWITCH Application filed September 18, 192,8.v Serial No. 300,626.

The present invention relates to switches, and particularly to that typeof switch in which mercury is used to make and break the circuit betweentwo terminals within a closed envelope.

creasing the cost of such switches in that cheaper glass, lead-in andelectrode material can be used -in the production of my new switches,such material also being more easily worked. Other objects will beobvious from an inspection of the accompanying speciiication anddrawings.

The invention consists in the novel arrangement and combination ofparts, as hereinaftor set forth and claimed.

Heretofore it has been usual to provide envelopes of hard glass, whichwere necessary to withstand the heat produced by the arc which occurswhen a circuit is opened while carrying a relatively large current suchas or 25 amperes, at 110 volts. By the introduction of suitable shieldsand baiiles of hard glass, quartz, porcelain, or the like according tothe present invention it is possible to use a soft glass envelope withsafety, al-

3 though such an envelope without the bailie cannot safely rupture muchover 5 amperes.

I have discovered that switches of the type disclosed herein and in myPatent 1,67 6.7 54 issued July 10, 1928 on an application filed June 17,1925, the present application being for improvements thereon, possessthe property of safely making and breaking when tilted or rotatedcircuits carrying 50 to 75 amperes, and when the improvements of myabove referred to patent and of this application are embodied in aswitch of the type disclosed in the Mailey Patent 1,537,921 is sued May12, 1925 and of the type disclosed in British Patent 183,683 circuits ofgreater amperage-can be safely made and broken, and

the added cost of production of the switch will be offset by the greatercurrent breaking property of the switch in continuous commerclal use ascompared with the amperages which hard or soft glass devices describedin the patents above referred to willsuccessfully make and break incommercial practice.

For the purpose of. illustration several switches embodying theinvention are shown in' the accompanying drawings, in which Fig. 1 is alongitudinal cross section of a switch embodying the invention,

Fig. 2 is a plan view of the bale shown in Fig. 1, l Fig. 3 is a frontview vof the same baiiie,

Fig. 4 is an end view thereof,

Fig. 5 is acentral vertical section, with the baiile shown in elevation,of a modification of Fig. 1 for larger current capacity,

Fig. 6 is a similar view to Fig. 5 of a switch of different design butembodying the invention, and v Fig. 7 is a longitudinal cross sectionwith the interior shield in elevation of a modication of Fig. 6 forlarger current capacity.

In all the figures the envelope is preferv ably formed of a soft glass,and may be either evacuated or filled with hydrogen, ammonia, nitrogenor other inert gas, in a manner well known to those skilled in the art.A filling of hydrogen or ammonia is, however, preferred. The inleads arepreferably formed of dumet, which is a nickel steel wire coated withcopper, and specially designed for sealing into soft glass but may be ofany other material having a suitable coeiiicient of expansion. Sincethecopper would impair the action of the mercury, the portion of saidinleads which `project within the envelope are preferably formed eitherof nickel previously welded to the dumet, or of nickel steel, exposed byremoving the copper coating from the dumet inside the container wallualthough other metals may be used without departing from this invention.The shields or barriers used in the various figures are either blown orl molded from hard glass, quartz, porcelain. or any suitable vrefractorymaterial, and are inserted within the envelopes before the ends of saidenvelopes are closed.

With .particular reference to Fi s. 1, 2, 3, 4 and 5 envelope 1 is oftubular s ape with closed ends. An inlead 2 of dumet enters saidenvelopev 1 through a reentrant seal 3 in the top of said envelope and alittle toward one end thereof. A similar inlead 5 enters said envelope 1through a reentrant seal 6 in the top of said envelope and adjacent to*he end more distant from inlead 2. A re-l fractory shield or baille 8,which is boatlike in shape, is located within said envelope 1 at thebottom thereof, with one end adjacent to the end of said envelope l1which isnearer inlead 2, and with the other end of said shield 8terminating near said inlead 5. A central depression 9 in shield 8 intowhich inlead 2 projects has an annular projection 10 extending upwardfrom the bottom thereof which engages with said inlead 2 whereby saidshield 8 is fixed in its position within said envelope 1. A longitudinalchannel 11 which is somewhat more shallow than depression 9 and which iscentrally disposed in the upper surface of shield 8 extends from thedepression 9 to the end of said shield 8 adjacent to inlead 5. Mercuryis provided in said envelope to a level slightly below the bottom ofsaid channel 11 when the switch is in the open position, as shown, andis thus divided into a pool 12 within the shield 8 in contact withinlead 2 and a pool 13 surrounding said shield and in contact withinlead 5. When the envelope is tipped slightly so as to tend to elevatepool 12 above pool 13 the mercury in pool 12 will run throu h channel 11and unite the two pools, thus c osing the circuit from inlead 2 toinlead 5. When the envelope is restored to the level positionillustrated, the mercury will run in the reverse direction throughchannel 11 until the bottom of channel 11 at the point where it opensinto depresfsion 9 is at the same lever as the mercury,

when the mrecury will thereby again be separated into the two pools 12and 13, and the arc will form betwen the two pools at that point. Itwill thus be seen that the arc is substantially conned to the depression9 and the channel 11 where the arc resisting shield 8 is effective inprotecting the soft glass envelope from the heat thereof.

The switch illustrated in Fig. 5 is designed for larger currents thanthat of Figs. 1, 2, 3 and 4, and in addition to being somewhat largerhas an additional protection for the soft glass envelope. A tubularliner 15 of quartz, hard glass or other refractory material is providedfor the envelope 1 and extoward the opposite end of said envelope 21.

A similar inlead 25 enters said envelope 21 at the bottom of the endopposite to seal 23 through the reentrant seal 26 and is curved so as toextend toward inlead 22. An arc shield 28 of hard glass, quartz orotherrefractory material is substantially tubular in shape,

with a bend toward one end thereof, said bent end opening upward toreceive the inlead 22 and a portion of seal 23. At said bent end shield28 is supported on the .bottom of envelope 21, while at the opposite enda curved bracket 29 of nickel or nickel steel welded to said inlead 25holds that end of said shield' 28 firmly against the top of saidenvelope 21, the tubular shield 28 being of such diameter that it willrest within said envelope 21 at a considerable angle therewith. Mercuris provided within said envelope to a evel slightly below the opening inthe straight end of said shield 28 when the envelope is in a levelposition, and is divided into a pool 30 inside of shield 28 in contactwith inlead 22, and a pool 31+ outside said shield in contact with theinlead 25. The walls of said. shield 28 rise around seal 23 to a heightsomewhat above the lowermost part of the opening in the opposite end ofsaid shield, so that the mercury pools 30 and 31 cannot mingle throughthat opening. When the envelope is tilted so as to tend to raise pool 30above pool 31 the Vmercury passes through the open end of shield 28 andmerges the two pools, thereby connecting inleads 22 and 25. When theenvelope is restored to the level position illustrated the mercury flowsin the reverse direction through said open end of shield 28 until thebottom thereof 1s at the same level as the mercury, when the mercurrated bythe end of said shie d 28 into the two pools 30 and-31, and anarc takes place between the two pools as the circuit is opened. As thepool 30 is receding rapidly at this time due to the sloping bottom ofthe shield 28 the are is drawn within said shieldr28 ,whereby saidenvelope 21 is shielded from the heat thereof.

Fig. 7 shows a modification of theswitch is again sepa.

of Fig. 6 which is designed to interrupt larger currents, and inaddition to being somewhat larger has a slightly different support; ingmeans for the sh1eld, as made necessar by a change in-structurewhicheven more e fectively shields said envelope from the arc.-

thereof is closed, and an opening 32 is `made in the bottom thereof nearthe end through which the mercury flows when the envelope is tipped.Inlead 25 engages with a projection 33 on the end of said shield 28 torigidly hold that end of said shield against the top of envelope 21.Mercury is provided to a height just below the lowermost point ofopening 82 when the envelope is level, forming the pools 3() and 31 asbefore. The operation is the same as that of the switch of Fig. 6, thebreak occurring between pools 30 and 31 over the lowermost point ofopening 32, so that the are is almost entirely enclosed within saidshield 28.

Greater sensitivity may be obtained in any of these switches by etchingthe portion of the barrier over which the mercury flows with hydrouoricacid previous to introduction within the envelope. The simplicity ofthis compared to etching the inside of the envelope as has been doneheretofore is obvious.

It will be observed that by the structure illustrated in the variousgures the inner` parts are fixed in position within the envelope withoutresort to packing.

When used on direct current the shielded inlead is connected to thenegative side of the line so that the hottest part of the arc is wellwithin the shield.

I claim:

l. In a mercury switch a tubular envelope,

Y a tubular lining within said envelope, leads sealed into saidenvelope, one of said leads forming an exterior support for said tubularlining, another of said leads terminating within said lining and mercuryin said envelope in sufficient quantity to frm a conducting path betweensaid leads when the switch is in a closed circuit position.

2. In a mercury switch a tubular envelope, a tubular lining within saidenvelope, .leads sealed into said envelope, one of said leads forming anexterior support for said tubular lining, another .of said leadsterminating within said lining, and mercury in said envelope insufficient quantity to form a conducting path between said leads whenthe switch is in a closed circuit position, said tubular lining being atsuch an angle with said envelope that the arc occurring upon opening ofthe circuit is drawn within said .tubular lining.

3. In a mercury switch a tubular envelope, a tubular lining within saidenvelope with one end closed and the other end upturned, leads sealedinto said envelope, one of said leads extending into said upturned endof said tubular lining, and another of said leads forming an exteriorsupport for said closed end of said tubular lining, an opening in thelower side of said tubular lining and Inercury within said envelope in aquantity sufficient to form a conducting path between said leads throughsaid opening when the Signed at Hoboken in the count of I-Iudi son andState of New Jersey this l th day of September A. D. 1928.

WARREN R. WALKER.

